HH250 consistently 38 miles/hour top end. PGO Bugrider 250 as standard 50 mph, limited by gearing, rev limiter on its TDCI module and of course European law (Max power 15KW and top speed 80 Kmh). With mods such as K&N filter, carb mods, straight intake system and Wileyco exhaust still 50 mph, but reached quicker.. Originally Answered: What is the top speed of a 250cc motorcycle? If it's got good aerodynamics, and you drop it from high enough, you can probably get up to about 450kph/280mph If you're talking "in a straight line", then the current record is 136MPH British rider attempting to break 250cc land speed record Charlie Davoine.